Size and Weight:
Just how "mega" was Megapiranha? Well, you may be disappointed to learn that this 10-million-year old piranha ancestor "only" weighed about 20 to 25 pounds, but you have to bear in mind that modern piranhas tip the scale at two or three pounds, max. Not only was Megapiranha at least ten times as big as modern piranhas, but it wielded its dangerous jaws with an additional order of magnitude of menace, according to a recently published study by an international research team.
The largest variety of the modern piranha, the black piranha, chows down on prey with a biting force of 70 to 75 pounds per square inch, or about 30 times its own body weight. By contrast, Megapiranha bit with a force of up to 1,000 pounds per square inch, or about 50 times its own body weight. (To put these numbers into perspective, one of the most fearsome dinosaurs that ever lived, Tyrannosaurus Rex, possessed a biting force of about 3,000 pounds per square inch, compared to a total body weight of about 15,000 pounds, or seven to eight tons.)
The only logical conclusion is that Megapiranha was an all-purpose predator of the Miocene epoch, chowing down not only on fish (and any mammals or reptiles foolish enough to venture into its river habitat) but also large turtles, crustaceans, and other shelled creatures. You can bet that somewhere right now, in Hollywood, an eager young director is casting Megapiranha: The Movie!